BNL Sun Power at BNL

Written on: June 1, 2012 by Paul J. Nazzaro

Sun Power at BNL
If you’ve ever seen the Syfy channel cable series Eureka, about a mythical, secret town in the U.S. populated by the nation’s most brilliant scientists, you might wonder whether such places really exist. Well, pretty much, they do. In fact, depending on how you count, the Department of Energy alone has 12 to 16 of them. While they may not have developed faster than light space drives or true artificial intelligence (at least we don’t think so), they are definitely doing research on the cutting edge. They’re our National Laboratories.
We are interested in one particular lab, the only one on the East Coast: Brookhaven National Laboratory (BNL). This facility, situated on the site of a World War I military base in Upton, New York (Long Island), sprawls over 5,320 acres with 330 buildings (and counting), employs over 2,800 individuals, educates 1,500 students and hosts 4,354 facility users. BNL’s advanced research covers the gamut from particle and nuclear physics, condensed matter physics and materials science, to climate change, nanoparticles , superconductors and a whole lot more.

Jon Longtin, Rebecca Trojanowski and Chris Brown with the integrated storage tank

And while Fermilab may be bigger, BNL’s Relativistic Heavy Ion Collider is the first machine in the world capable of colliding ions as heavy as gold. Down the road, a brand new, $900 million-plus facility, still under construction, will accommodate the National Synchrotron Light Source II (NSLS II), probably the most advanced facility for studying light physics in the world (it will be able to produce the brightest light on earth, among other things). So without a doubt, some very high level research is Sun power at BNL Brookhaven National Laboratory’s Energy Conservation Group is evaluating a solar thermal ‘combisystem’ which could provide heat and hot water while saving significant fuel in the process. R&D / SOLAR / COVER FEATURE done at BNL. We mention the NSLS II because directly across the street, in a few older buildings, you will find another bit of advanced research. They house the Energy Conservation Group, in which is located the Oilheat Research Lab. It’s run by Dr. Tom Butcher. His division researches all methods of producing energy as efficiently as possible, including some very exotic science—and the labs are not limited to heating oil exclusively. In fact, the subject of this report is the division’s Solar Thermal Project. Begun approximately two years ago, it uses solar thermal, along with a high efficiency oilfired condensing boiler, to provide heat and hot water for a building on the research campus.

Conference room radiant heating Sponsors include the New York Energy Conservation and Development Authority (NYSERDA), The DoE Federal Energy Jon Longtin, Rebecca Trojanowski and Chris Brown with the integrated storage tank Photo: Mike SanGiovanni, ICM Large photo: Mike SanGiovanni, ICM; inset: BNL 18 ICM/June 2012 Management Program, BNL facilities and Rotex GmbH (the German manufacturer of the system tested). The project was designed to evaluate a “combisystem” which integrates solar collectors, a condensing boiler, storage, low temperature heat distribution and con- trols in “system to meet space heating and domestic hot water loads.”

Indoor Comfort Marketing’s Editor, Mike SanGiovanni, visited BNL to discuss the project with the team members. Dr. Jon Longtin hosted the visit, accompanied by Chris Brown, Rebecca Trojanowski and George Wei. Other team members involved in the project include Yusuf Celebi, Mark Toscano, Chris Channing, Dan Farge and Chuck Schuster.

Designing the project

Dr. Longtin said one of the major project goals is to evaluate such combisystems, which are common in Europe, but not in the U.S. The idea is to implement the European model and see if it is worthwhile to implement here, with a secondary goal of extracting a realistic view of the practicality of combisystems. For example, one concern is how robust the system is in terms of maintaining its design efficiency if portions of the system are not functioning at their optimal level, or the system parameters are not set correctly. “These are complicated systems, with operating decisions being made by several separate controllers across the system,” Longtin said. “It only takes one incorrect setting or outof- bounds parameter to significantly alter the system behavior.”
Finally, taking all they learned from the project, a third goal would be to determine how it could be improved; in essence, they were creating a future research tool.
Once they established the direction the project would take, it became a matter of how to best implement the testing procedure. They decided to test in a real-life situation, rather than simulating conditions in the lab. They wanted a building that was in use.
The first step was to find the right building for a field test, and, since there are more than 300 at BNL, they had a pretty good chance of locating what they needed. The ideal building would need solar exposure, which basically translates to having a flat roof. And roof accessibility was important, as adjustments to the solar collectors would most likely be needed on occasion.
The building also needed a connection to the mechanical room and ideally, it needed a satellite building with a local boiler and water heater. The building chosen was “The Brookhaven Center” and it filled the bill quite well: This building used to be the Officers Club when the lab was an Army Training Base in World War II. It is now used regularly at a meeting and conference center.
The main building, of original wood frame construction with a sloped room on a concrete slab, features two later additions, both of concrete block with flat roofs and partial basement.
The local boiler provided steam heat and consumed 11,000 gallons of fuel oil annually to heat the 14,295 ft2 space.

Solar collectors

One of the flat roofs was ideal for placement of the solar collectors. It was only one story up, accessible by short ladder, and the collectors could be positioned for maximum sun gain. Five solar collectors were installed. They were supplied as part of the combisystem by Rotex (model V26A Flat Plate). The five collectors (photos, right and on following page) collectively provide 13 square meters total area and the panels are of the dry design (more on that below).

The boiler

The Boiler
The unusual Rotex design, with its cast aluminum shell and stainless steel tubes, is, as are many European boilers, a condensing type fired by a low-NOx blue flame burner firing B-20 (20% biofuel/80% no. 2 fueloil). The new boiler, said Chris Brown, is roughly 92% efficient. Its primary role is space heating, with supplemental heat for the domestic hot water system.

Heat distribution

One conference room was chosen. It had considerable window exposure and a slab floor. The slab was retrofitted with radiant PEX tubing over which was poured a concrete floor. The radiant valve distributes heated water to four zones beneath the floor, heating the room more quickly and uniformly, although the four zones are not individually controlled.

Integrated storage tank

The integrated storage tank, a 500 liter (132 gallon) unit provides hot water for the radiant heating and for domestic hot water. It features three separate coils within the tank. The main body of the unpressurized tank is filled with ordinary tap water, which is heated by the Solaris unit via the roof panels. The tank contains three individual coils. One is a stainless steel coil running the entire length of the temperature stratified tank. Water is circulated from the older oilfired hot water heater through this coil, which is surrounded by water heated Left and below, Mike SanGiovanni, ICM; radiant installation: BNL BNL BNL The Brookhaven Center, a former Officer’s Club, is now a conference center. Radiant was installed in the main meeting room. ICM/June 2012 19 by the Solaris unit and, if necessary, by a second stainless steel heat exchanger (from the boiler) that supplements on cloudy days.
A third, smaller coil is used for the space heating requirements. It’s smaller because radiant doesn’t require extremely hot water. The diagram on the facing page shows the coil arrangement.

Drainback System

As mentioned above, the roof solar thermal panels use a drainback system, in which water drains by gravity back to the storage tank once heat is no longer requested from the collectors.. This means there’s no water in the panels to freeze in the winter. One of the parameters of the project was to avoid the use of antifreeze, so the dry design was essential. Water used is ordinary tap water, with no additives.
The drawback to such a system is that if the panels are dry during a sunny day, they can get too hot to use. If they become too hot, the system will not circulate water through them because they would heat the water instantly to steam, causing unwanted pressure. They have to cool down to a usable temperature before water can circulate through them.

Some lessons learned

Below, main boiler is at left. HI-efficiency condensing boiler is center and old oilfired water heater is at right.

A great many parameters were measured, including optimum angle for the solar collectors, oil usage with and without various components operating, and so on. What the team found, so far, was that the most effective domestic hot water mode was with the boiler off and the solar tank acting as a preheater for the Bock oilfired hot water tank. The BNL Plant Engineering (Facilities) group preferred this design because it ensured that the building would have hot water if the solar combi system failed.
With the afternoon domestic hot water draw pattern, the tank heats in the morning and the collectors often shut down by noon. With drain back, where the collectors are emptied of water, the system collectors cannot turn on again until the next day due to their heat gain.
In the space heat mode, the solar is used to supplement the boiler (thus reducing its load and fuel use). The team says the measured collector efficiency is close to nominal.
The plan now is to eliminate the fuel-fired domestic hot water heater altogether and rely solely on the solar hybrid.

Monitoring the system

The building housing the solar thermal project is located some distance from the lab, but Brookhaven has an impressive integrated system in its intranet that allows monitoring of building systems throughout the complex.

Cross-sectional drawing above of integrated Storage Tank showing how three coils are employed in greater detail.

The research team can monitor the entire process from any computer station, and all parameters of the project, such as system pumps and valves,
can be controlled remotely. If they decide to cut out the radiant for a test, or bypass the water heater, a few clicks of the mouse are all that are needed.
Sometime near the end of the year, the data, now being compiled, will be in and conclusions drawn.
Currently, the United States and Canada are the only developed nations that maintain a high base of warm air units. Europe, on the other hand, is moving heavily into condensing hydronic systems. Knowledge gained from BNL’s research may help the U.S. oilheat industry in its goal to achieve more efficient technology at reasonable cost.

New research lab

: New lab building

The task of finding more efficient boilers, heat exchangers, burners and the like will become easier in the Energy Conservation Group’s new lab. In a short while, the team that tests the latest developments in home and commercial heating will be moving to new, larger quarters. The new building will house two key research laboratories where a number of boilers can be set up for efficiency testing. This is the part of the division that provides research for various clients, such as NORA, DoE, NYSERDA and the like.

Fuel tanks and storage

Some of the projects currently under way include a self sustaining boiler, as an example. Chris Brown explained that one of the problems with any heating system that uses electrical power (to run fans and pumps) is a shutdown when there is a power failure. A project underway would seek to employ components that require very little electrical input. Once running, the flame from the unit might heat a special ceramic panel in the combustion chamber which, when it gets hot enough, would glow. The light emitted from that glow would presumably be bright enough to excite photocells which could then generate enough electricity to keep the system running in case of power failure. There are some obstacles. Gallium arsenide photocells are used in the test apparatus, but they are extremely rare and expensive (gallium is rarer than gold), so such factors must be taken into account. Other considerations include finding motors that require very little power to operate.

Lab D7

In another test, he said, an ammonia water heat pump, supplemented by a liquid fuel, could result in an extremely efficient system (more than 100%) and it looks promising. Initial applications may be commercial rather than residential at this point.
Rebecca Trojanowski described another project that seeks to develop a plastic heat exchanger (using a polymer loaded with carbon nanotubes). It appears quite promising. This is important research because condensing boilers can produce corrosive condensate, which can adversely affect metallic heat exchangers. A plastic version would be impervious to such acidic liquids.

Lab D8

And Chris Brown said there is work designed to examine the combustion efficiency of pyrolysis oil (a tar-like synthetic fuel made from biomass- to-liquid technology, and used as a substitute for petroleum).
Currently, the lab is also evaluating the efficiency of woodburning devices with the aim of reducing particulate matter in the exhaust stream, so the research is not all about oil by any means.